Adding a subwoofer to your audio system will be a profound improvement. That is a statement that is true almost regardless of the size and bass capabilities of your main speakers. In this article I will attempt to explain some of the reasons.  .

Room acoustics and placement

The overall listening experience is hugely impacted by room acoustics. The placement of your main speakers within the room and relative to the listening position is fundamental. Since this article is about subwoofers, I won’t go into details about the positioning of the main speakers. However it should be clear that there are certain restrictions to placement options within a normal living environment that will satisfy the practicality and aesthetics as well as the listening experience. There is a very good chance that the placement of choice is not the acoustical ideal but rather a compromise.

Adding a subwoofer  gives you not only the freedom of moving the excitation source of the room modes, but the excitation source is also shared between more sources i.e. left speaker, right speaker and subwoofer(s). In other words room modes are far more manageable with a subwoofer.

Aren’t subwoofers for movies?

All recent movie audio tracks are mixed specifically with a subwoofer in mind, making the subwoofer a must have for anyone serious about their movie experience. It is less obvious how a subwoofer will improve your two channel music listening experience. It’s not as simple as adding more bass extension and volume.

Even recordings that don’t appear to have a great deal of bass will still benefit and blossom with the added weight, impact and dynamics of a great subwoofer.

A properly integrated, quality subwoofer will enhance the sound of your main speakers, adding  to the depth and width of the sound stage, as well as making instruments and vocals sound more natural and true to life.

Sealed or ported designs

Whether a sealed or a ported design is the best choice is a controversial topic, simply because there is no clear cut winner – it all depends on what you are aiming for, and what equipment you need to integrate with.

The sealed design’s main advantages: superior transient response (tighter bass) and smaller size.

The smaller physical size of a sealed subwoofer has its obvious advantages with regards to placement and aesthetics. For pure musicality the sealed subwoofer usually comes out on top due to its faster transient response.

The ported design has two main gratifications: efficiency and better extension (goes louder and deeper).


Sealed and ported box comparison

To make a ported design that performs well and sounds right, the enclosure volume must be considerably bigger, and the tuning frequency set low enough not to influence transient response too much in the mid-bass area. This means we end up with a quite large subwoofer that may be hard to integrate in small and midsize rooms, and will need to be mated to exceptionally capable main speakers to accomplish good integration. However, if these limitations are dealt with, a ported subwoofer can be a very gratifying weapon of choice. More often than not, a bad sounding, ported subwoofer is not because of the ported principle itself, but simply a result of bad design.

Getting the settings right

If you are aware of the presence of the subwoofer when listening to music, then the settings are not correct. Here are a few pointers to get things dialed in a little quicker by being methodical:

  1. Choose a piece of music you know well, and that has a good balance of bass, instruments and vocals.
  2. Start with the crossover frequency a little higher than what you think you might end up with, and also the volume a little higher than what is optimal. This way you can hear the subwoofer clearly which can help dial in the crossover frequency.
  3. Now turn down the crossover frequency in small increments until it is a little too low, then dial it back up just a tad. A too high crossover will make the subwoofer sound shouty or tubby, and will start to influence the lower midrange in a negative way. A too low crossover will make the bass sound thick and limp with lack of attack.
  4. With the crossover frequency now at a reasonable level turn down the volume in small increments until you can no longer distinguish the sub from the main speakers.

To get the perfect balance may take quite a bit of fiddling using different music and extended listening. However the above method should get you pretty close fairly quickly.

Signal processing and equalization

This is a huge subject, and something that is developing quite fast within the high end audio segment. Digital signal processing is not at all new, but during recent years it has become a lot more mature for use in home audio systems. The ease of use of most systems is now impressive, and we have seen advancements in knowledge of psycho acoustics as well as giant leaps forward in terms of DSP hardware capabilities and affordability.

This does not necessarily mean that you need to invest in a room correction system. I have seen examples where a great room correction system had little merit, due to the fact that there  was very little to correct in the given setup. A great audio system that is optimally placed in a room with great acoustic properties will benefit very little from room correction and equalization. However, if you have an acoustically challenging environment, and you are for one reason or another not able or willing to address this by physical means such as rearranging speakers, furniture and adding room treatment such as acoustic absorbers, diffusors,  etc., then Digital Signal Processing may be a great option.

Everyone deserves a subwoofer

Whether for home theater duties or for musical bliss, you will be thrilled by the improvement a good subwoofer will make. The subwoofer is never to draw attention to itself but will make the musical experience blossom.